Analysts also cited weakness in the dollar as a boost for petroleum prices following Federal Reserve meeting minutes released Wednesday that suggested central bankers would remain cautious on raising interest rates.

Oil is traded internationally in the US currency. A weaker dollar boosts demand for crude outside the US.

"Brent has climbed... to US$50 per barrel for the first time since early July, finding support from a weaker US dollar and an unexpectedly marked decline in US crude oil and gasoline stocks," said Commerzbank analyst Carsten Fritsch.